1. Field of the Invention
The present invention concerns epoxy-amine adducts for use as emulsifiers for epoxy resins; epoxy resin dispersions on an aqueous basis using said emulsifiers and a process for their production.
2. Description of the Related Art
It is known to produce synthetic resins by emulsion polymerization and to produce stable aqueous dispersions of these resins in that one stabilizes the resin in the aqueous phase by the addition of suitable dispersing agents or by incorporated hydrophilic groups. In the case of condensates such as epoxy resins, which are difficult to produce by emulsion condensation, one must resort however to other processes. One of the most frequently used processes is the dispersion of a condensation reaction produced polyglycidyl ether based upon multifunctional (i.e., polyhydric) alcohols, phenols, hydration products of these phenols and/or of novolac and the like, in the aqueous phase with use of one or more suitable dispersing agents or, as the case may be, emulsifiers. Such epoxy resin dispersions are generally quite unstable and tend after a short period of time to precipitation of the binder, in particular at temperatures above 25.degree. C. The resulting epoxy resin dispersions exhibit as a rule particle sizes of more than 1 .mu.m thus tend, after several weeks or, as the case may be, several months in storage, to coalesce, to increase in particle size, and therewith to a deterioration of the film forming properties.
Several of these epoxy resin dispersions can, for reduction of viscosity and increasing dispersion stability, also have reactive thinners added thereto during their production. These are however, because of their toxic properties and because of generally high vapor pressure, undesirable in view of their workplace hygienic properties. Besides this, the chemical properties of the hardened epoxy resin films are often negatively influenced by these reactive thinners. Conventionally available epoxy resin dispersions further contain solvents, benzyl alcohol and glycols or glycol ethers and the like, which are also undesirable.
Water soluble and aqueous based epoxy resin systems assumed increasing importance due to the above discussed disadvantages and due to environmental concern discussions and corresponding changes in the state of the law in Germany and Europe.
In BE-OS 4310198 it is for example described, that special non-ionic emulsifiers, which are polyol-epoxy addition products of (A) an aliphatic diol with an average molar mass of 200 to 20000 g/Mol and of (B) an epoxy compound with at least two epoxy groups per molecule and an epoxy equivalent weight of 100 to 2000 g/Mol and an equivalent ratio of the OH-groups to the epoxy groups of 3:3.5 to 1:10 and wherein the epoxy equivalent weight of the addition product lies between 150 g/Mol and at least 8000 g/Mol, are particularly suitable for use in aqueous soluble epoxy fluid resin systems. Said aliphatic polyol (A) are polyether polyols (poly alkylene glycols), the epoxy compounds (B) are polyglycidyl ethers on the basis of di-valent alcohols or of novolac resins, with bisphenol A being particularly preferred. The above described emulsifiers are produced by the condensation of polyether polyols (A) with the epoxy compound (B) in the presence of suitable catalysts.
By mixing the so obtained emulsifiers with epoxy-fluid resins on the basis of bisphenol A- and bisphenol F-glycidyl ethers on obtains a self emulsifying fluid resin system, which would polymerize with aqueous soluble amine resins, for example polyamines and polyoxyalkylene di- and poly-amines with molecular weights of 100 to 2000 (JEFFAMINE.RTM., Texaco Corporation.) to films with good properties, which find use above all as protective coatings for mineral primers or undersurfaces.
In DE-OS4309639 aqueous based epoxy resin dispersions are described, which contain:
(A-1) an epoxy resin, which is a condensation product which is comprised of:
(A-1-a) 50 to 90 wt. % of one or more epoxy compound(s) with at least two epoxy groups per molecule and an epoxy equivalent weight of 100 to 2000, PA1 (A-1-b) 5 to 50 wt. % of an aromatic polyol and, if desired, PA1 (A-1-c) 0 to 25 wt. % of modified compounds with at least two epoxy reactive groups,
(A-2) a dispersing agent in the form of a condensation product of an aliphatic polyol with an average molecular weight (Mw) of from 200 to 20,000 and an epoxy compound with at least two epoxy groups per molecule and a epoxy equivalent weight of 100 to 2,000 wherein the equivalent ratio of the OH-groups to the epoxy groups is 1:0.8 to 1:3.5 and wherein the epoxy equivalent weight of this condensation product lies between 5,000 and 400,000 g/Mol,
(B) a carboxyl group-containing or -releasing hardening agent for the epoxy resin (A-1), comprised of one or more carboxyl group-containing compound(s), wherein at least one of these compounds exhibits a functionality of at least three carboxyl groups and
(C) if desired, conventional additives,
wherein the components (A-1), (A-2) and (B) are employed in such weight amounts, that the equivalent ratio of the epoxy groups to the carboxyl groups participating in the reaction represents at least 1:0.5.
In the compounds according to (A-1-c) these are concerned with compounds for the targeted modification of the base resin (A-1) for example polyamine, poly(alkylene oxide) with terminal amino groups (for example JEFFAMINE.RTM., of Texaco Corporation.), polycarboxylic acids and their anhydrides and the like. Their employment can occur, in order that by targeted modifications desired characteristics of the base resin (A-1) can be adjusted.
The described non-ionic stabilized dispersions of the aqueous epoxy resins (A-1) plus (A-2) produce, in a combination with the special polyvalent carboxylic acids (B), coating combinations, which can be hardened to particularly high value coatings.
In the European Patent document EP 0 109 173 there is described a hardenable two component epoxy resin compound on aqueous basis, of which the components are separately stored and mixed prior to use.
The first part, the component (A) or the base resin, is comprised of a glycidylether of Bispenol A or a derivative thereof. The diglycidyl ether is partially reacted with a polyoxy alkylene amine. The second part, the component (B) or the hardening agent, is comprised of a reactive polyamide polyamine.
The modified epoxy resin (A), which is converted or reacted with the polyoxyalkyl amine, acts as emulsifier, while at the same time retaining much of its epoxy functionality. This is an advantage with respect to the state of the art, which typically requires non-reactive emulsifiers for the formation of the aqueous based systems. The polyoxyalkyl amine is a block copolymer of ethylene oxide and propylene oxide with primary amino groups in the terminal positions, for example, a mono-amine (JEFFAMINE.RTM., M-Series of Texaco Corp.) or a diamine (JEFFAMINE.RTM., ED-Series of Texaco Corp.).
Part (B) of the two component composition or a mixture comprises a reactive, aqueous compatible polyamide polyamine, which is produced by reaction of multifunctional carboxylic acids, esters, anhydrides or mixtures thereof with a polyvalent amine, which can be aliphatic, cyclo- aliphatic or aromatic, or with mixtures thereof.
Upon hardening of base (A) with hardener (B) clear or colored highly glossy coatings are produced.
In U.S. Pat. No. 5,459,208 elastic hardened epoxy resin compounds are described, which comprise:
(A) reaction products of (A1) compounds with at least two 1,2-epoxide groups per molecule with parent (A2) polyoxyalkyleneonoamine with number average molecular weights of &gt;900 g/mol, werein the polyoxyalklyenemonoamine contains a mol fraction of up to 20% of polyoxyethylene units, based on the total amount of polyoxypropylene and polyoxyethylene units, and, when desired, with (A3) polycarboxylic acids, and
(B) hardeners and, when desired,
(C) conventional additives.
As epoxy component (A1) there are preferably employed glycidyl ethers, which are derived from bisphenol and novolac resins, of which the epoxy equivalent weight is between 150 and 500 g/mol. There can also be employed polyglycidyl ethers on the bases of aliphatic alcohols. Preferred polyoxyalkylene monoamines (A2) are monoamine-block co-polymers, which contain oxypropylen and oxyethylene groups and which are obtainable from Texaco Chemical Co. under the trademark JEFFAMINE.RTM. M-series, for example JEFFAMINE.RTM. M-2005 with a molecular weight of approximately 2000 g/mol and an oxypropylen-oxyethylen ratio of 32/3.
Recently the importance of cold hardening, water soluble and aqueous, two-component based epoxy resin systems has strongly increased.
Therefore, it is the task of the present invention to provided emulsifiers for production of aqueous soluble and aqueous based epoxy resin components, with which epoxy resin dispersions can be obtained, which are non-ionicaly stabilized, solvent-free and, besides this, provide an exceptionally low viscosity system.